In the case
of phase modulation there are two nonzero components of the real and
imaginary parts of excitation [>>]. The splitting network multiplies
the input signal by a constant and makes it as as argument of cosine in the
real component and the sine in the imaginary component. This network includes
nonlinear elements. Nevertheless, for small signal analysis, the cosine of
small angle is approximately one, and the sine of small angle is
approximately angle itself. Thus for real component we have a constant
[>>] And for imaginary component – the input signal multiplied by
constant [>>]. This network is linear and suitable for AC analysis,
using phasor input VAC [>>].